Make sure the dough to be fried is not laden with flour; when the dough is placed in the hot oil, the excess flour will burn, accumulate in the pan, and cause the frying medium to degenerate quickly.
Prepare a slotted spoon or a skimmer and a pan covered with paper towels at the same time you begin heating the oil, so that everything needed to drain the pastries is ready before you begin frying. Fried pastries cook quickly and may burn if left unattended while you search for a pan on which to drain them.
Use a large, deep pan, like a Dutch oven, for frying. Fill the pan only halfway at most; this way if the fat begins to foam, it will not overflow.
Use a low-to-medium heat for heating frying fat. Never use a high heat, which might cause the flame to jump up the side of the pan and ignite the fat.
Use a thermometer to gauge the heat of the fat, and adjust the heat under the pan accordingly as the temperature fluctuates during frying.
Severe burns may result if the pan of hot fat is jostled or if the fat splashes during frying. Make sure children, pets, and the idly curious are well away from the kitchen when you are deep-frying.
After you finish frying, remove the pan of hot fat from the hot burner to a cool one. Cover the pan and allow the fat to cool. If you have used oil, cool and filter it through a coffee filter or paper towel and use a funnel to pour it back into a bottle; cork it tightly and refrigerate. If the oil has burned or darkened excessively, discard it by pouring it down the drain accompanied by running hot water.
Use fried pastries for informal and family occasions, so that you may enjoy them freshly fried and warm. Some fried pastries, like cannoli, may be prepared well in advance, but Sfingi, Frittelle di Riso Corrado Costanza, and some others are best served immediately.